Engine Boiled over

[1969 300]

I get the ac condenser on my 300 installed, and the ac works fine now. When I drive home the engine boils (thermometer said 245). Anyone know how I can fix this?

 

[detmatt]

Try not to let it get that hot again as that's not good for your engine. Start by checking the thermostat and the general condition of your lower radiator hose. If its really soft and there's no spring inside it to keep it from collapsing you should replace it.

 

[1969 300]

Which thermostat should I run in hot weather? it currently has a 195.

 

[detmatt]

I'd knock it back 10 degrees to 185.

 

[detmatt]

And make sure you're running the proper coolant mixture.

 

[1978 NYB]

Stant has 160, 180, and 195 degree thermostats which can be bought at any parts store. I would go with the 180. Be sure you get a gasket......they are a separate item these days. I would also get a new radiator cap......one without the red lever.

 

[Red63440]

I get the ac condenser on my 300 installed, and the ac works fine now. When I drive home the engine boils (thermometer said 245). Anyone know how I can fix this?

Do you have a shroud on the engine?

 

[360dusted]

Be careful before you just throw a cooler t-stat in there, a properly working cooling system shouldn't overheat whether the t-stat is 160 or 195*. It sounds like you might have an airflow problem; if the engine overheats at lower speeds it's usually airflow, at higher speeds usually cooling system problems. Make sure the radiator isn't clogged or the fins smashed up and the shroud is in place. Make sure the idle step-up is working when you turn on the A/C as that helps it run cooler when stopped.

 

[detmatt]

Good info and advice 360dusted. He's 100% correct, a 195 with a properly functioning system should treat you right all season long. That being said I'd still put the 180 in it in case the system isn't always working optimally.

 

[commando1]

Having to run a 160 thermostat tells me there is something wrong elsewhere. It's a band-aid.

 

[fc7_plumcrazy]

make sure to use a lot of anti freeze, it cools better than with "just" water even if it is not needed (like in Califronia, Arizona, NW, TX etc)

Carsten

 

[1978 NYB]

Is this a problem that just started or has this car not been running in a long time?

 

[cm23uoc]

make sure to use a lot of anti freeze, it cools better than with "just" water even if it is not needed (like in Califronia, Arizona, NW, TX etc)

Carsten

My experience has always been the other way round. The more antifreeze, the higher the water temp.

 

[polara71]

because it holds the heat longer, a 50/50 mix is usually the best thing

 

[1969 300]

To answer everyones questions, yes it has a shroud. The car has been running a little hot, but nothing like this. I noticed when the engine was boiling, some coolant was bubbling from the rad cap, so I will replace it and the thermostat, and check the radiator.

 

[detmatt]

There's an additive called Water Wetter that I've heard good things about but this would obviously be another bandaid.

 

[360dusted]

My experience has always been the other way round. The more antifreeze, the higher the water temp.

This is true, water alone has a lower boiling point than coolant but it holds a lot more heat thus having the ability to cool down your engine better. You can try adding more water to make it like a 60/40 but again if you need to do that for it to work there is something else wrong...

You said coolant was bubbling from the rad cap, as in it was leaking? If so that would definitely cause your car to overheat, if it can't hold pressure properly the coolant will boil over more easily. BTW I'd recommend a 10-lb. cap (as opposed to 16-lb that is the standard) if you are still running the original radiator. The lower pressure will help keep your 40-year-old radiator from leaking.

 

[1978 NYB]

If you have to play with the antifreeze mix you have bigger problems than that. It could be anything from a thermostat or a radiator cap. Do you have a fan clutch? Those are overlooked all the time. Are you sure the antifreeze isn't leaking out of the water pump weep hole? Someone mentioned if you had a spring in the lower radiator hose......the hose can collapse without a spring in it.

 

[commando1]

There's an additive called Water Wetter that I've heard good things about but this would obviously be another bandaid.

Water Wetter has been exposed as another Snake Oil.
A few drops of Dawn will do the same thing.

 

[polara71]

If the thermostat isnt working you are gonna overheat which is why that is what was recommended first. Pull the stat, put it in a pot of boiling water and watch it open up, if it doesnt open, it needs a new one. Otherwise move on from there.